This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 11-088569, filed Mar. 30, 1999; and No. 11-096060, filed Apr. 2, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to an optical wiring layer through which light propagates, an optoelectric wiring substrate comprising the optical wiring layer and a substrate having an electric wiring, a mounted substrate in which an optical part or the like is mounted on the optoelectric wiring substrate, and methods for manufacturing each of these structures.
In the field of electric elements such as semiconductor large-scale integrated circuits (LSI), the degree of integration of transistors has been increasing. Some semiconductor large-scale integrated circuits Among these LSIs are those which operate at so high a clock frequency as 1 GHz.
To mount highly integrated electric elements on an electric wiring substrate, packages such as BGAs (Ball Grid Arrays) and CSPs (Chip Size Packages) have been developed and put to practical use.
In general, the inter-element signal speed outside an electric element increases linearly with the clock frequency inside the electric element. The increase in inter-element signal speed induces noise such as reflection arising from the inappropriate shape of an electric wiring joining elements together, or cross talk. Another problem may occur that this increase causes an increased amount of electromagnetic waves to be generated from the electric wiring to adversely affect the surroundings. Thus, in constructing systems, the signal speed between electric elements is diminished enough to prevent these problems. As a result, highly integrated electric elements cannot fully provide their functions.
In order to solve these problems, the following methods have been contemplated: Part of an electric wiring on an electric wiring substrate is replaced with an optical wiring comprised of optical fibers so that optical signals are used instead of electric signals. This is because optical signals do not cause noise or electromagnetic waves.
An example of this method if disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 9-236731. This is a method for forming optical waveguides on an electric wiring substrate. Specifically, optical waveguides are directly formed on a ceramic multilayer wiring substrate (in the order of a clad layer, a core pattern, and a clad layer).
Multiple layers of electric wirings, however, are formed on a surface of the electric wiring substrate, which acts as an under layer of the optical wiring layer. This electric wiring forms very large recesses and projections. Thus, disadvantageously, when the optical waveguides are formed on the electric wiring substrate, the propagation loss of optical waves increases.
The present invention is provided in view of these circumstances, and it is an object thereof to provide an optical wiring layer, an optoelectric wiring substrate, a mounted substrate, and methods for manufacturing these structures wherein the propagation loss of optical signals is small and wherein high-density mounting and size reduction can be achieved.
The present invention is an optoelectric substrate comprising a substrate having an electric wiring and an optical wiring layer laminated on the substrate, the optical wiring layer comprising: a core through which light propagates; a clad for holding the core; a mirror for reflecting light propagating through the core; first conductive installation means formed on a surface of the optical wiring layer for installing light-receiving means for receiving light reflected by the mirror or light-emitting means for emitting light toward the mirror; and connection means for electrically connecting the first conductive installation means to the electric wiring.
According to this optoelectric wiring substrate, an optical wiring layer is laminated on a substrate having an electric wiring, in addition, conductive installation means, which install an optical part on the optical wiring layer, are provided. The optical part installed on the conductive installation means is electrically connected to the electric wiring.
Accordingly, with this configuration, the optical wiring layer is laminated on the substrate with the electric wiring. As a result, high-density mounting and size reduction can be achieved.
Another optoelectric wiring substrates according to present invention are as follows:
(1) The present invention is An optoelectric substrate comprising a substrate having an electric wiring and an optical wiring layer laminated on the substrate, the optical wiring layer comprising: a core through which light propagates; a clad for holding the core; a mirror for reflecting light propagating through the core; second conductive installation means formed on a surface of the optical wiring layer for installing an electric part; and connection means for electrically connecting the second conductive installation means to the electric wiring.
According to this optoelectric wiring substrate, an optical wiring layer is laminated on a substrate having an electric wiring, in addition, conductive installation means, which install an electric part on the optical wiring layer, are provided. The electric part installed on the conductive installation means is electrically connected to the electric wiring.
Accordingly, with this configuration, high-density mounting and size reduction can be achieved.
(2) The present invention is an optoelectric substrate comprising a substrate having an electric wiring and an optical wiring layer laminated on the substrate, the optical wiring layer comprising: a core through which light propagates; a clad for holding the core a mirror for reflecting light propagating through the core; first conductive installation means formed on a surface of the optical wiring layer for installing light-receiving means for receiving light reflected by the mirror or light-emitting means for emitting light toward the mirror; second conductive installation means formed on the optical wiring layer surface for installing an electric part; connection means for each of the conductive installation means to the electric wiring.
According to this optoelectric wiring substrate, an optical wiring layer is laminated on a substrate having an electric wiring, in addition, first conductive installation means for installing an optical part and second conductive installation means for installing an electric part, are provided. The optical part and the electric part installed on each of the conductive installation means are electrically connected to the electric wiring.
Accordingly, with this configuration, high-density mounting and size reduction can be achieved.
(3) The present invention is an optoelectric substrate comprising a substrate having an electric wiring and an optical wiring layer laminated on the substrate, the optical wiring layer comprising a first clad; a first core formed on the first clad through which light propagates; a mirror for reflecting light propagating through the first core; a second core formed on the first clad using a material identical to that of the first core; first conductive installation means laminated on the second core for installing light-receiving means for receiving light reflected by the mirror or light-emitting means for emitting light toward the mirror; connection means for electrically connecting the first conductive installation means to the electric wiring, and a second clad for holding at least one of the first clad, the first core, the mirror, the second core, and the connection means.
According to this optoelectric wiring substrate, an optical wiring layer is laminated on a substrate having an electric wiring, in addition, conductive installation means, which install an optical part on the optical wiring layer, are provided. The optical part installed on the conductive installation means is electrically connected to the electric wiring.
Accordingly, with this configuration, high-density mounting and size reduction can be achieved.
(4) The present invention is an optoelectric substrate comprising an optical wiring layer laminated on a substrate having an electric wiring, the optical wiring layer comprising a first clad; a first core formed on the first clad through which light propagates; a mirror for reflecting light propagating through the first core; a second core formed on the first clad using a material identical to that of the first core; second conductive installation means laminated on the second core for installing an electric part; connection means for electrically connecting the second conductive installation. means to the electric wiring, and a second clad for holding at least one of the first clad, the first core, the mirror, the second core, and the connection means.
According to this optoelectric wiring substrate, an optical wiring layer is laminated on a substrate having an electric wiring, in addition, conductive installation means, which install an electric part on the optical wiring layer, are provided. The electric part installed on the conductive installation means is electrically connected to the electric wiring.
Accordingly, with this configuration, high-density mounting and size reduction can be achieved.
(5) The present invention is an optoelectric substrate comprising an optical wiring layer laminated on a substrate having an electric wiring, the optical wiring layer comprising a first clad; a first core formed on the first clad through which light propagates; a mirror for reflecting light propagating through the first core; a second core formed on the first clad using a material identical to that of the first core; first conductive installation means formed on the second core for installing light-receiving means for receiving light reflected by the mirror or light-emitting means for emitting light toward the mirror; second conductive installation means formed on the second core for installing an electric part; connection means for electrically connecting the each of the connection means to the electric wiring, and a second clad for holding at least one of the first clad, the first core, the mirror, the second core, and the connection means.
According to this optoelectric wiring substrate, an optical wiring layer is laminated on a substrate having an electric wiring, in addition, first conductive installation means for installing an optical part and second conductive installation means for installing an electric part, are provided. The optical part and the electric part installed on each of the conductive installation means are electrically connected to the electric wiring.
Accordingly, with this configuration, high-density mounting and size reduction can be achieved.
(6) The present invention is an optoelectric wiring substrate comprising: a substrate having an electric wiring; a first optical wiring layer laminated on one of the surfaces of the substrate and having a core through which light propagates and a clad for holding the core; a second optical wiring layer laminated on the other surface of the substrate and having a core through which light propagates and a clad for holding the core; a third optical wiring layer penetrating the substrate in a perpendicular direction and having a core through which light propagates and a clad for holding the core; a first mirror formed to extend through the first optical wiring layer and the third optical wiring layer for reflecting light; propagating through one of the optical wiring layers, to the other optical wiring layer; and a second mirror formed to extend through the second optical wiring layer and the third optical wiring layer for reflecting light propagating through one of the optical wiring layers, to the other optical wiring layer.
According to this optoelectric wiring substrate, the third optical wiring layer penetrating the substrate in a perpendicular direction is connected the first optical wiring layer laminated on one of the surfaces of the substrate and the second optical wiring layer laminated on the other surface. In each of connection areas between the cores, a mirror for reflecting light propagating through one of the optical wiring layers to the other optical wiring layer is provided.
Accordingly, with this configuration, light is reflected by the mirror and propagates the third optical wiring layer so that light can propagate from one of the surfaces to the other surface.
Incidentally, it is preferable that each of the optoelectric wiring substrates further comprises alignment means formed a material to that of the core for using alignment with the substrate having the electric wiring.
Furthermore, it is preferable that each of the optoelectric wiring substrate further comprises alignment means formed a material to that of the first core for using alignment on forming of the mirror.
The above construction can implement an optical wiring layer, an optoelectric wiring substrate, a mounted substrate, and methods for manufacturing these structures wherein the propagation loss of optical signals is small and wherein high-density mounting and size reduction can be achieved.
In addition, the present invention is an optical wiring layer comprising: a first optical wiring layer having a core through which light propagates and a clad for holding the core; a second optical wiring layer having a core through which light propagates and a clad for holding the core, the second optical wiring layer being connected to the first optical wiring layer at a predetermined angle; and a mirror formed to extend through the first optical wiring layer and the second optical wiring layer for reflecting light propagating through one of the cores, to the other core.
According to this optical wiring layer, the second optical layer is connected to the first optical layer at a predetermined angle. In connection area between the cores, a mirror, which reflects light propagating through one of the cores, to the other core, is formed.
Furthermore, it is possible that the present invention is an optoelectric wiring substrate comprising: the optical wiring layer according to claim 14; and a substrate having an electric wiring on which the optical wiring layer is laminated.
Accordingly, with this configuration, high-density mounting and size reduction can be achieved.
Furthermore, it is possible that the present invention is a mounted substrate comprising: the optical wiring substrate and an optical part installed on the first conductive installation means for receiving light reflected by the mirror or emitting light toward the mirror.
Accordingly, with this configuration, high-density mounting and size reduction can be achieved.
Furthermore, it is possible that the present invention is a mounted substrate comprising: the optical wiring substrate; and an electric part installed on the second conductive installation means for receiving light reflected by the mirror or emitting light toward the mirror.
Accordingly, with this configuration, high-density mounting and size reduction can be achieved.
The above construction can implement an optical wiring layer, an optoelectric wiring substrate, a mounted substrate, and methods for manufacturing these structures wherein the propagation loss of optical signals is small and wherein high-density mounting and size reduction can be achieved.
The present invention is a method for manufacturing an optoelectric wiring substrate, comprising the steps of: forming an optical wiring layer on a smooth first support substrate; forming a mirror for reflecting light propagating through the optical wiring layer; releasing the optical wiring layer from the smooth first support substrate and sticking the optical wiring layer on a substrate having an electric wiring; and forming conductive installation means on the optical wiring layer for installing an optical or electric part to be mounted on the optoelectric wiring substrate, the conductive installation means being electrically connected to the electric wiring.
According to this method for manufacturing an optoelectric wiring substrate, after being manufactured on the flat first support substrate, the optical wiring layer is stuck to the substrate with the electric wiring. Thus, the effect of recesses and projections of the electric wiring on the substrate can be lessened compared to an optical wiring layer directly manufactured on the substrate with an electric wiring).
Another optoelectric wiring substrates according to present invention are as follows:
(1) The present invention is a method for manufacturing an optoelectric wiring substrate, comprising the steps of: forming an optical wiring layer on a smooth first support substrate; releasing the optical wiring layer from the smooth first support substrate, and sticking a surface of the optical wiring layer on a smooth second support substrate using a first adhesive; applying a second adhesive to one of substrates having an electric wiring; sticking the other surface of the optical wiring layer on the second adhesive; and releasing the smooth second support substrate and the first adhesive from the optical wiring layer.
According to this method for manufacturing an optoelectric wiring substrate, the optical wiring layer is fixed to the smooth second support substrate so as to be stuck to the electric wiring substrate while maintaining its smoothness.
With this configuration, the optical wiring layer of the optoelectric wiring substrate is not affected by the unevenness of the underlying electric wiring substrate surface. The propagation loss of optical signals can be minimized.
(2) The present invention is a method for manufacturing an optoelectric wiring substrate, comprising the steps of: forming an optical wiring layer on a smooth second support substrate; applying a adhesive to a substrate having an electric wiring; sticking the optical wiring layer on the adhesive; and releasing the smooth second support substrate from the optical wiring layer.
According to this method for manufacturing an optoelectric wiring substrate, the optical wiring layer is fixed to the smooth second support substrate so as to be stuck to the electric wiring substrate while maintaining its smoothness.
With this configuration, the optical wiring layer of the optoelectric wiring substrate is not affected by the unevenness of the underlying electric wiring substrate surface. The propagation loss of optical signals can be minimized.
(3) The present invention is a method for manufacturing an optoelectric wiring substrate comprising the step of: forming a first through-hole in a substrate having an electric wiring; forming first clads on both surfaces of the substrate and filling a clad in the first through-hole; forming a second through-hole in the first through-hole which has a smaller inner diameter than the first through-hole; covering the clad with a core layer to fill the second through-hole with a core, in order to obtain an optical wiring extending along the substrate and an optical wiring penetrating the optical wiring; removing portions of the core layer which are not used as the optical wirings, in order to expose the first clad; forming a second clad on exposed portions of the first clad and core layer, the second clad having a refractive index equal to that of the first clad; and forming a mirror for reflecting light from the optical wiring extending along the substrate to the optical wiring penetrating the optical wiring.
In addition, the present invention is a method for manufacturing an optoelectric wiring substrate comprising the step of: forming a release film on a smooth support substrate; forming a first optical wiring layer on the release layer which comprises a first core through which light propagates in a first direction and a clad for holding the first core; forming a hole in the first optical wiring layer which is inclined at a predetermined angle relative to the first optical wiring layer; filling a core in the hole to form a second core through which light propagates in a second direction; forming a mirror such that light from the first core is incident on the second core for reflecting light propagating through one of the optical wiring layers, to the other optical wiring layer; and releasing the optical wiring layers from the smooth support substrate.
The optoelectric wiring substrates according to each of the method of manufacturing can guide light from one surface of the substrate having the electric wiring to the other surface.
The above construction can implement an optical wiring layer, an optoelectric wiring substrate, a mounted substrate, and methods for manufacturing these structures wherein the propagation loss of optical signals is small and wherein high-density mounting and size reduction can be achieved.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.